Firefighters battling the massive Rim fire continued to make significant headway and expect to fully contain the blaze in the next two weeks, the California Department of Forestry and Fire Protection said Wednesday afternoon.

Crews on the ground were aided by cooler weather, higher relative humidity and lighter winds, which have helped slow the explosive rate of spread that characterized the blaze last week, Cal Fire spokesman Daniel Berlant said.

"That's given us a greater opportunity to get in there and strengthen our containment lines," he told The Times.

He said fire commanders expect full containment of the blaze by Sept. 10.

Last week, the fire burned 30,000 acres in a 24-hour span and 50,000 acres in another 24-hour span, Berlant said. But in the last two days, the rate of fire spread has slowed to 10,000 acres one day and 5,000 on another.

As of Wednesday, the Rim fire had raged across more than 187,000 acres of brush and timber and was 23% contained. The fire had charred more than 40,000 acres in Yosemite National Park.

At least 111 structures have been destroyed by the fire, which has been burning since Aug. 17.

Fire crews in Yosemite were hoping to slow advancing flames by conducting large-scale backfire operations from Hetch Hetchy Reservoir south to Tioga Road. The dangerous tactic involves setting fires inside containment lines to burn vegetation in the path of advancing flames and stop the spread of the blaze.

On the other side of the massive fire near California 108, ground crews aided by an aggressive air attack reported making considerable headway in their struggle to build and strengthen containment lines.

"We're making great progress along the fronts that are threatening the Highway 108 corridor," Berlant said.